Heat exchanger

ABSTRACT

A heat exchanger of the single circuit type, to be coupled to a fluid circulation circuit and comprising: an upper tubular head element and a lower tubular head element horizontally arranged and which are each provided with a nozzle and through slots provided in an inner longitudinal wall portion; and a plurality of vertically disposed fluid conduction tubes, each internally defining a plurality of longitudinal microchannels. The opposite ends of the fluid conduction tubes are affixed to the inner longitudinal wall portion of the upper tubular head element and lower tubular head element, respectively, so as to communicate the ends of the microchannels of each tube with a through slot of the respective tubular head element and, thus, the fluid conduction tubes with the interior of the upper tubular head element and lower tubular head element.

CROSS REFERENCE TO PRIOR APPLICATIONS

This application claims priority to Brazilian Patent Application No. PI0700912-7, filed on Mar. 13, 2007, the disclosure of which isincorporated herein by reference.

1. Field of the Invention

The present invention refers to a heat exchanger of the single circuittype to be used as a condenser or as an evaporator, in diverseapplications, particularly in air conditioner appliances, aiming tofacilitate the manufacture and to improve the heat exchange efficiency.

2. Prior Art

Nowadays, the heat exchangers manufactured with fluid conduction tubesof oval flat section, containing microchannels, are horizontallyarranged with corrugated fins, being coupled to the vertically arrangedhead elements, at the side ends of the fluid conduction tubes, whichform more than one circuit or are manufactured in the coil typeconfiguration.

This type of heat exchanger assembly, besides being of high industrialcomplexity, has the limitation of not being able to work as anevaporator, since the oval flat fluid conduction tubes withmicrochannels have a flattened form and are mounted with corrugatedfins, retaining the water condensed from air moisture therebetween,impairing the operation of the heat exchanger and making unfeasible itsapplication as an evaporator.

These heat exchangers also have high resistance to the dragging ofrefrigerant fluid condensed in its interior, provoking high load lossesin the refrigerating circuits, and demanding a higher power from thecompression equipment.

SUMMARY OF THE INVENTION

As a function of the inconveniences mentioned above and regarding theknown constructive solutions for the heat exchangers of theabove-considered type, the present invention has the object of providinga heat exchanger of the single circuit type, which is easy to constructand which presents more versatility in order to be used as a condenserand as an evaporator, improving the heat exchange efficiency in any ofsaid applications, by using the same basic elements defined by tubularhead elements that are coupled to and communicate with the ends of aplurality of fluid conduction tubes.

The object above is attained by the provision of a heat exchanger of thesingle circuit type, to be coupled to a fluid circulation circuit andcomprising: an upper tubular head element and a lower tubular headelement, which are horizontally arranged and have closed ends, eachtubular head element being provided with a nozzle for connection to thefluid circulation circuit, and a plurality of through slots provided inan inner longitudinal wall portion of the respective tubular headelement and which are transversal to the longitudinal axis of thetubular head element; and a plurality of fluid conduction tubes ofsubstantially elongated rectangular cross-section and verticallyarranged side-by-side, each fluid conduction tube internally defining aplurality of longitudinal microchannels with open ends, the oppositeends of said fluid conduction tubes being affixed against the innerlongitudinal wall portion of the upper and lower tubular head elements,respectively, so as to tightly communicate the ends of the microchannelsof each fluid conduction tube with a through slot of the upper and lowertubular head elements, respectively, and thus the fluid conduction tubeswith the interior of the upper and lower tubular head elements.

The construction proposed herein improves the heat efficiency of theheat exchanger due to the arrangement and to the increase of the numberof fluid conduction tubes in the same area and to the reduction of theload loss of the refrigerant circuit, as a consequence of the singleunidirectional circuit through the fluid conduction tubes, i.e., withoutchanging direction and also due to the fact that the condensedrefrigerant flows directly downwards, when the heat exchanger operatesas a condenser, efficiently separating the gaseous part from the liquidpart and further permitting the refrigerant fluid, evaporated in thegaseous state, to flow directly upwardly, when the heat exchangeroperates as an evaporator, also efficiently separating the phases ofgas+liquid mixture from the saturated or superheated gas. Thisarrangement of fluid conduction tubes in the vertical position can beapplied to condensers and evaporators of vapor-compression refrigeratingand/or heating systems, since, in the case of the application as anevaporator, all the water condensed at the surface of the tubes willflow by gravity, thus leaving the surface free for a more effective heatexchange.

The present constructive solution further contributes to a betterefficiency of the ventilation system, mainly when applied to forcedventilation systems, since it has less resistance to air passage, thuscontributing to reduce the dimensions and the power required for themotor of the air impeller, which is generally defined by a fan.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described below, with reference to the encloseddrawings, given by way of examples of possible embodiments of thepresent heat exchanger and in which:

FIG. 1 represents a front top perspective view of the heat exchanger;

FIG. 2 represents a front view of the heat exchanger of FIG. 1;

FIG. 2A represents an enlarged detail view of the lower end of the heatexchanger of FIGS. 1 and 2, taken according to the limits defined by thecircle “A” illustrated in FIG. 2;

FIG. 3 represents an elevation view of the right side of the heatexchanger of FIGS. 1-2A;

FIG. 4 represents, simultaneously, a top plan view and a lower plan viewof the inner longitudinal walls of the lower and upper tubular headelements, respectively, of the heat exchanger of FIGS. 1-3, deprived ofthe fluid conduction tubes;

FIG. 4A represents an enlarged detailed view of an end of the lower andupper tubular head elements of the heat exchanger of FIGS. 1-4, takenaccording to the limits defined by the circle “B” illustrated in FIG. 4;

FIG. 5 represents an enlarged cross sectional view of the fluidconduction tube of the heat exchanger of FIGS. 1-4A; and

FIG. 6 represents an enlarged cross sectional view of a constructivevariant for the fluid conduction tube of the heat exchanger of theprevious figures.

DETAILED DESCRIPTION OF THE INVENTION

As already previously mentioned and illustrated in the encloseddrawings, the invention refers to the construction of a heat exchangerto be used as a condenser or as an evaporator in several applications,particularly in air conditioner appliances, said heat exchanger being ofthe single circuit type.

According to the present invention, the heat exchanger comprises anupper tubular head element 10 and a lower tubular head element 20,constructed in any adequate material, such as for example, carbon steel,stainless steel, thermoplastic material, etc., and which arehorizontally arranged and have their ends closed, so that each tubularhead element defines a tube extension whose cross section can varyaccording to the heat exchanger project. In the embodiment illustratedin the drawings, the upper tubular head element 10 and the lower tubularhead element 20 present a rectangular cross section, having an innerlongitudinal wall 10 a, 20 a turned to the heat exchanger structure andwhich, in the case of the embodiment of rectangular section, defines aflat surface, also of rectangular contour. The upper tubular headelement 10 and the lower tubular head element 20 each further presents,in said construction of rectangular cross section, an outer longitudinalwall 10 b, 20 b, turned outwardly from the heat exchanger body orstructure.

Each upper tubular head element 10 and lower tubular head element 20 isprovided, generally in one of its closed ends, with a nozzle 11, 21, forconnecting said upper tubular head element 10 and lower tubular headelement 20 to a fluid circulation circuit with which the heat exchangeris operatively associated. These nozzles 11, 21 can present differentconstructions that are well known in the prior art, its particularconstruction not being a relevant aspect to the object of the presentinvention.

As illustrated in the enclosed drawings, each upper tubular head element10 and lower tubular head element 20 presents, in an inner longitudinalwall portion 10 a, 20 a, a plurality of through slots 12, 22 arrangedtransversal to the longitudinal axis of the respective tubular headelement, said through slots 12, 22 generally presenting an elongatedrectangular contour that is similar to and slightly smaller than that ofthe fluid conduction tubes 30. The through slots 12, 22 are arrangedside-by-side, each extended substantially over the whole width of theinner longitudinal wall 10 a, 20 a of the respective upper tubular headelement 10 and lower tubular head element 20. In case of constructingthe tubular head elements with a rectangular cross section, the throughslots 12, 22 present an extension which substantially corresponds to thewidth of the inner longitudinal wall of the tubular head element.

The present heat exchanger further comprises a plurality of fluidconduction tubes 30 presenting a substantially elongated rectangularcross-section and being vertically arranged side-by-side. Each fluidconduction tube 30 is constructed so as to internally define a pluralityof longitudinal microchannels 31 with open ends coinciding with the endsof the respective fluid conduction tube 30, the opposite ends of saidfluid conduction tubes 30 being affixed, by any adequate process, suchas brazing, against the inner longitudinal wall portion 10 a, 20 a ofthe upper tubular head element 10 and lower tubular head element 20,respectively, so as to allow the occurrence of a tight fluidcommunication between the ends of the microchannels 31, of each fluidconduction tube 30, with a through slot 12, 22 of the upper tubular headelement 10 and lower tubular head element 20, respectively and,consequently, between the fluid conduction tubes 30 and the interior ofthe upper tubular head element 10 and lower tubular head element 20through the through slots 12, 22.

As illustrated, the present construction allows the fluid conductiontubes 30 to be arranged side-by-side, with its longitudinal extensionparallel to the direction of the airflow passing through the spacingsdefined between said fluid conduction tubes 30 and along their sidewalls, thereby facilitating the airflow through the heat exchanger,without the existence of elements which cause undesired load loss to thethrough airflow. In order to facilitate airflow, the fluid conductiontubes 30 can be constructed with their opposite end longitudinal edges32 tapered or simply configured in a convex arc, as illustrated in FIGS.5 and 6 of the enclosed drawings. The fluid conduction tubes 30 can beconstructed with externally smooth side walls or also incorporatingsmall projecting side fins 33, extending along at least a substantialpart of the height of the fluid conduction tubes 30. These smallprojecting side fins 33 are formed in the material that constitutes therespective fluid conduction tubes 30, considerably facilitating theconstruction of said elements and allowing an effective increase in itsheat exchange outer surface area.

It should be understood that, in the case of providing fluid conductiontubes 30, such as in the construction illustrated in FIG. 6, the spacingbetween each pair of adjacent fluid conduction tubes 30 is designed todefine an adequate distance between the free ends of the confrontingsmall projecting side fins 33, so as not to impair the heat exchangeairflow passing between said fluid conduction tubes 30 of the heatexchanger.

While only two possible constructive forms of the present heat exchangerhave been illustrated herein, it should be understood that alterationscan be made in the form and physical arrangement of the elements,without departing from the constructive concept defined in the claimsthat accompany the present specification.

1. A heat exchanger of the single circuit type, to be coupled to a fluidcirculation circuit, comprises: an upper tubular head element and alower tubular head element which are horizontally arranged and haveclosed ends, each tubular head element being provided with a nozzle forconnection to the fluid circulation circuit, and with a plurality ofthrough slots provided in an inner longitudinal wall portion of therespective tubular head element and which are transversal to thelongitudinal axis of the tubular head element; and a plurality of fluidconduction tubes, of substantially elongated rectangular cross-section,vertically arranged side-by-side, each fluid conduction tube internallydefining a plurality of longitudinal microchannels with open ends, theopposite ends of said fluid conduction tubes being affixed against theinner longitudinal wall portion of the upper tubular head element andlower tubular head element, respectively, so as to tightly communicatethe ends of the microchannels of each fluid conduction tube with athrough slot of the upper tubular head element and lower tubular headelement, respectively, and thus the fluid conduction tubes with theinterior of the upper tubular head element and lower tubular headelement.
 2. The heat exchanger, as set forth in claim 1, wherein theupper tubular head element and lower tubular head element present arectangular cross section.
 3. The heat exchanger, as set forth in claim2, wherein the through slots present an elongated rectangular contour,similar to and slightly smaller than that of the fluid conduction tubes.4. The heat exchanger, as set forth in claim 3, wherein the throughslots are arranged side-by-side, each extending substantially over thewhole width of the inner longitudinal wall of the respective uppertubular head element and lower tubular head element.
 5. The heatexchanger, as set forth in claim 2, wherein the through slots present anelongated rectangular contour, similar to and slightly smaller than thatof the fluid conduction tubes.
 6. The heat exchanger, as set forth inclaim 1, wherein the nozzle is arranged in one of the closed ends of theupper tubular head element and lower tubular head element.
 7. The heatexchanger, as set forth in claim 1, wherein the fluid conduction tubeshave opposite end longitudinal edges in convex arc.
 8. The heatexchanger, as set forth in claim 1, wherein the fluid conduction tubesincorporate small projecting side fins extended along at least asubstantial part of the height of the fluid conduction tubes.